Preparation And Characterization Of Composite Wave-absorbing Materials Based MWCNTs

In this paper, to measure absorbing property in the low-frequency （0～6GHz）, MWCNTscomposites modified with magnetic metal, Zn/Co spinel ferrite and conductive polymer wereprepared.（1） PANI/CNTs was prepared by in situ low-temperature static system, the results ofX-ray diffraction （XRD）, Raman specture analyses demonstrated that PANI particles werecovered on the surface of the MWCNTs successfully.（2） Exploration the effect of MWCNTs content, doped acid type, monomer concentrationon the specific morphology of composites preparation process, it has been found thatcomposites obtained the best morphology with 15% carbon nanotube content, compositesappeared obvious needle-like morphology when doped acid was sulfanilic acid andslenderness ratio increased with the reduction of aniline monomer concentration.（3） Consideration of the influence of MWCNTs content and doped acid type on thethermal stability of PANI/CNTs, it indicated that both MWCNTs and doped acid canimprove the thermal stability of PANI and doped acid made much impact. The sample with10% MWCNTs and sulfanilic acid doped acid had best thermal stability.（4）The proportion of nickel and cobalt, activation method, temperature and pH valuewere determined to prepare MWCNTs electroless plating with nickel/ cobalt. The results ofscanning electron microscope （SEM）, intuitive experiment and microwave absorbingproperty analyses determined that optimum craft was as follow: silver activated carbon nanotubes, pH value was 9, pH value was 9.5 when the mole ratio of Ni to Co was 1:4,plating temperature was 80℃, the mole ratio of Ni to Co was 4:1，the MWCNTs waspretreated in a mixed acid solution and was heated directly.（5） Investigating the microwave absorbing properties of electroless plating carbonnanotubes and polypyrrole composites, obtained Ni8Co2/CNTs had the largest reflectionloss, -15.6db, Ni/ CNTs had much larger peak width of R﹤-5db, 1.8GHz, andNi8Co2/CNTs/PPy had best reflection loss, -19.9db, which indicated the absorption intensityof electroless plating MWCNTs enhanced with the existence of PPy.（6） Exploration the effect of proportion of zinc and cobalt, MWCNTs content on themagnetic properties of Zn_xCo_1-xFe₂O₄ /CNTs, it has been found the saturation magnetizationfirst increased and then decreased with the content of zinc increasing, coercive forceincreased with the content of cobalt increasing. When x value was 0.5 and 0.2, thecomposites possessed the largest saturation magnetization and coercive force, respectively,38.86emu/g, 539.66Oe.With the content of MWCNTs increasing, the saturationmagnetization and coercive force reduced and increased respectively.（7） When x value was 0.5, the composites possessed the best microwave absorbingproperty: the largest reflection loss reached -32.40 dB and the peak width of R﹤-5db and R﹤-10 dB was more than 2GHz, 1GHz, respectively. When the content of MWCNTsincreased to 20%, the reflection loss decreased to -10 dB.